In general, mobile terminals can be freely-used regardless of places while a user moves. Mobile communication terminals such as mobile phones and personal digital assistants (PDAs) that are referred to as personal portable terminals are typical mobile terminals. The words “mobile terminal” used herein include all the above devices. However, in the following description, the words “mobile terminal” are limited to the PDAs for the convenience of explanation.
In a complicated and diverse society, individuals need to keep or maintain information for one's own purpose. A variety of products are released in a market to meet the needs of individuals and one of the products is a PDA. The PDA is referred to as a pocket computer and signifies a palm size compact device having a calculation function or an information storing and search function for a personal use or business use. Usually, the PDA is widely used to maintain schedule calendar and address information.
In particular, PDAs for an industrial use are widely used mainly for logistics industry and the market is gradually expanding. The industrial PDA has multiple office functions such as a bar code scanner or a card reader that is not present in a general PDA. The use of the industrial PDA makes delivery, information management, and other related business efficient. For example, in an insurance company, an insurance planner can process various insurance related business such as client information management, client search, schedule management, consultation diary management, celebration day search, and fund calculation process, directly at the site using the industrial PDA. In a hospital, medical staff members can input or search patient treatment records, a case history, and an image or graphic material such as an X-ray image, using the industrial PDA without a limit in time and place. In the business of police, the use of the industrial PDA can remarkably reduce the outside duty time of a traffic or guard policeman by making a fine for a violation of traffic rules paid immediately at a bank which would have been paid after 2-3 days from disposition.
The industrial PDA which is widely used in the above-mentioned diverse industrial fields must meet requirements over a predetermined level to endure industrial environment that is not a general environment unlike the general PDA. That is, unlike the general PDA, the industrial PDA may be used in a refrigerator under −10° C. or below or outdoors for a long time. Also, since a postman, for example, may toughly use the industrial PDA, the industrial PDA must have anti-shock, waterproof, and anti-heat/freezing functions over a predetermined level so as to have a competition. Thus, the industrial PDA must be manufactured more firmly and hard than the general PDA and necessarily has a waterproof function to endure snow or rain. Accordingly, since the industrial PDA is designed to meet the above requirements such as anti-shock, waterproof, and anti-heat/freezing functions over a predetermined level and a barcode scanner needs to be installed as described above, the size of the PDA is normally relatively large so that the size of the general PDA need to be reduced for the Asian users whose hands are relatively smaller than those of Westerners.
However, for a conventional mobile terminal, in particular, the industrial PDA, to have a waterproof function, a gap between an upper casing and a lower casing is sealed by coating a sealing member during an assembly process. Thus, in this technique, since the coating is manually performed, a manufacturing process becomes complicated. Also, when the upper casing and the lower casing are disassembled for repair, since the gap needs to be coated again with the sealing member, reassembly is deteriorated. Furthermore, the structure of the industrial PDA becomes complicated and it is difficult to reduce the size of a product of this type.